dimension lookup/update inserts duplicate rows

I am currently using Dimension Lookup-Update step.
I have the "Update the dimension" check box enabled.
In the Fields tab,
When the "Type of the dimension update" is "Insert"
I think it is supposed to insert a new dimension record version only if One or more attributes were different.
But, in my case,
eventhough I have the same set of data, a new row is being inserted.

Am I missing something? Correct me if my understanding is wrong.

Thanks,
Om
----------------------
Spoon version -4.3.0
DB2 v9.5.0.808
Windows XP

Well, make sure to never offer rows of data out of order. That is NOT supported.